Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	MQ-135
Detection Gases	Ammonia, Sulfide, Benzene, Smoke, CO2
Operating Voltage	5V DC
Output Signal	Analog and Digital (TTL)
Preheat Time	24-48 Hours
Sensitivity Adjustment	Potentiometer Included
Interface Type	3-Pin Header (VCC, GND, OUT)
PCB Dimensions	32mm x 20mm
Compatibility	Arduino, Raspberry Pi, ESP32
Package Contents	1x MQ-135 Module, 1x Pin Header Strip

6 reviews

Anonymous

Mar 25, 2026

Rating: 4/5

Good value but needs patience

The module is solid and well-soldered. Just remember that you must let it preheat for at least 24 hours before trusting the data. Once warmed up, it detects smoke and alcohol vapors instantly.

Anonymous

Mar 23, 2026

Rating: 3/5

Works but gets hot

The sensor functions well, but the heating element gets quite warm to the touch. Make sure your enclosure has some ventilation holes. Otherwise, no complaints about performance.

Anonymous

Mar 23, 2026

Rating: 5/5

Great sensitivity

I tested this against a professional meter and the relative changes were very accurate. Excellent for detecting cooking fumes or poor ventilation in small rooms.

Anonymous

Mar 15, 2026

Rating: 4/5

Useful for monitoring

Using this in my greenhouse to monitor ammonia levels from compost. It triggers my exhaust fan reliably when thresholds are met. Would buy again.

Anonymous

Mar 15, 2026

Rating: 5/5

Perfect for my home automation project

This sensor works exactly as described. I connected it to my Arduino Uno and had readings within minutes after the initial preheat. The sensitivity adjustment pot is very responsive.

Anonymous

Mar 09, 2026

Rating: 5/5

Easy to integrate

Plug and play with ESP32. The analog output provides a smooth curve for graphing air quality over time. Documentation online is plentiful for this specific model.

5 FAQ

Q: Can this detect carbon monoxide specifically?

A: The MQ-135 is sensitive to a broad range of harmful gases including CO, but it is not specific to Carbon Monoxide alone. For dedicated CO detection, an MQ-7 sensor is recommended.

Q: What is the power consumption?

A: The heating element typically draws about 150mA at 5V. Please ensure your microcontroller or power supply can handle this current load.

Q: Does this module output I2C data?

A: No, the MQ-135 module outputs analog voltage and a digital TTL signal. For I2C communication, you would need an external ADC converter or a different sensor variant.

Q: Is the pin header included in the package?

A: Yes, the package includes one MQ-135 module and a strip of 3-pin headers which you can solder onto the board yourself.

Q: How long does the preheat time really need to be?

A: For stable and accurate readings, we recommend a preheat time of 24 to 48 hours. Shorter periods may result in fluctuating baseline values.

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